1:1 Adducts of 1-naphthol and (Na)phthalaldehydic acid

ABSTRACT

This invention relates to derivatives of phthalaldehydic and naphthalaldehydic acid useful as intermediates in the preparation of pH-sensitive phthalide and naphthalide indicator dyes. One class of intermediates provided by the present invention comprises compounds of the formula: ##SPC1## 
     Wherein A represents 4&#39;-hydroxy-1&#39;-naphthyl and X represents the atoms necessary to complete a ring-closing moiety selected from a phthalide and a naphthalide and preferably is naphthalide. 
     Another class of intermediates provided by the present invention comprises compounds of the formula: ##SPC2## 
     Wherein A represents 4&#39;-hydroxy-1&#39;-naphthyl; B represents 4&#39;-hydroxy-1&#39;-naphthyl or indol-3-yl and C represents a 2-carboxy-1-phenyl radical or an 8-carboxy-1-naphthyl radical and preferably is 8-carboxy-1-naphthyl.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation-in-part of our copending applicationSer. No. 202,615 filed Nov. 26, 1971, now U.S. Pat. No. 3,816,453.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a novel method of preparing indicator dyes andto novel intermediates useful in the preparation thereof.

2. Description of the Prior Art

Dyes which undergo a change in spectral absorption characteristics inresponse to a change in pH are well known in the art, and frequently,are referred to as indicator or pH-sensitive dyes. Typically, these dyeschange from one color to another, from colored to colorless or fromcolorless to colored on the passage from acidity to alkalinity or thereverse and are commonly employed in analytical chemical procedures tomeasure changes in pH value. Among the indicator dyes most widely usedis the group derived from phthaleins as exemplified by phenolphthalein,thymolphthalein, cresolphthalein and 1-naphtholphthalein.

Though various methods have been used for synthesizing phthaleinindicator dyes, they are generally prepared via the Friedel-Craftsreaction by condensing the selected phenol or 1-naphthol with phthalicor naphthalic acid, their anhydrides or acid chlorides at elevatedtemperature in the presence of a suitable catalyst, for example, zincchloride or sulfuric acid to yield the corresponding symmetrical, i.e.,bis-phenol or bis-naphthol phthalide or naphthalide. Unsymmetricalphthalieins and mixed phthalein indicator dyes, such as,benzene-resorcinol phthalide are prepared in a similar manner bycondensing an o-aroyl benzoic acid dye intermediate with the selectedphenol also in the presence of a suitable catalyst, such as, sulfuricacid at elevated temperature.

The present invention is concerned with a new method of synthesizingcertain phthalein indicator dyes, namely, 1-naphthol phthalides andnaphthalides.

SUMMARY OF THE INVENTION

It is, therefore, the primary object of the present invention to providea novel method of synthesizing indicator dyes.

It is another object of the present invention to provide a method ofsynthesizing 1-naphthol phthalides and naphthalides which may besymmetrical, unsymmetrical or mixed indicator dyes.

It is a further object of the present invention to provide novelintermediates useful in the preparation of such dyes.

Other objects of this invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the process involving the severalsteps and the relation and order of one or more of such steps withrespect to each of the others and the product possessing the features,properties and the relation of elements which are examplified in thefollowing detailed disclosure and the scope of the application of whichwill be indicated in the claims.

According to the present invention, a method of preparing indicator dyesis provided wherein (a) a p-(na)phthalidylnaphthol is reacted with (b) acompound selected from a 1-naphthol and an indole in the presence ofbase to form a leuco dye intermediate which is then oxidized to form thecorresponding 3,3-disubstituted (na)phthalide. The expressions"(na)phthalidyl" and "(na)phthalide" as used herein are intended todenote either the phthalidyl-substituted naphthol and the phthalide dyeobtained therefrom or the naphthalidyl-substituted naphthol and thenaphthalide dye obtained therefrom depending upon the para substituentof the naphthol reactant (a).

Because the reaction conditions are milder than those normallyencountered in prior art procedures, the present method allows greaterlatitude in the selection of 1-naphthol reactants. For example, the moresensitive naphthol compounds, such as, those containing carboxysubstituents may be employed as the (a) and/or (b) reactant without theloss of the carboxy group(s) and the formation of susbstantial amountsof decarboxylated by-products that usually occurs under Friedel-Craftsconditions. Since the present method is limited to the more stablecompounds, it allows greater latitude in the dyes that may be producedwhich includes not only symmetrical or bis naphthol (na)phthalides butunsymmetrical and mixed indicator dyes as well.

For a fuller understanding of the nature and objects of the presentinvention reference should be had to the following detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the present invention, it has been found that a second moleof a 1-naphthol or a mole of indole may be added to the 1:1 adduct of a1-naphthol and a (na)phthalaldehydic acid and that the leuco dyeintermediate thus obtained may be oxidized to yield the corresponding(na)phthalide indicator dye. Because naphthols are not stronglynucleophilic in nature, the base-catalyzed addition of a second mole ofnaphthol to a p-(na)phthalidyl naphthol is quite unexpected. Moreover,1-naphthol indicator dyes wherein both naphthyl radicals posses carboxysubstituentes may be produced in this manner without any substantialamount of decarboxylation as normally encountered in prior processes.

In one embodiment, the method of the present invention comprises:

1. reacting (a) a compound of the formula: ##SPC3##

wherein A represents a 4'-hydroxy-1'-naphthyl radical and X representsthe atoms necessary to complete a ring-closing moiety selected from aphthalide and preferably, a naphthalide and (b) a compound selected froma 1-naphthol having a free para position and an indole having a free3-position in the presence of base to form a leuco dye intermediate ofthe formula ##SPC4##

wherein B is a radical selected from 4'-hydroxy-1'-naphthyl andindol-3-yl; C is a radical selected from 8-carboxy-1naphthyl and2-carboxy-1-phenyl; and A has the same meaning given above; and

2. treating said leuco dye intermediate with an oxidizing agent to formthe corresponding indicator dye having the formula: ##SPC5##

wherein A, B and X have the same meaning given above.

In another embodiment of the present invention, compound (a) in step (1)above is prepared by reacting a 1-naphthol and a (na)phthalaldehydicacid in the presence of an acid catalyst.

In a preferred embodiment of the present invention, 3,3-disubstitutedphthalides and naphthalides are produced wherein the 3,3 substituentsare 3'-carboxy-4'-hydroxy-1'-naphthyl radicals, the same or different.In this embodiment, the naphtholic --OH groups of the leuco dyeintermediate preferably are ionized prior to oxidation of theintermediate to form the indicator dye product.

The reaction scheme of the present method is illustrated below whereinB'--H represents the 1-naphthol or indole which ultimately comprises theB radical in the final dye; C represents a 2-carboxy-1-phenyl radical##SPC6##

or an 8-carboxy-1-naphthyl radical ##SPC7##

and X represents the atoms necessary to complete a phthalide ornaphthalide ring-closing moiety. Step (1a) represents the additionalionization step in the production of carboxy-naphthol dyes wherein thep-(na)phthalidyl naphthol contains a carboxy group ortho to thenaphtholic --OH and B'--H comprises a 1-naphthol also containing acarboxy group ortho to the naphtholic --OH. ##SPC8##

Typical of the indicator dyes that may be prepared according to thepresent invention are those represented by the formula: ##SPC9##

wherein A represents a 4'-hydroxy-1'-naphthyl radical; B represents aradical selected from 4'-hydroxy-1'-naphthyl and indol-3-yl; and Xrepresents the atoms necessary to complete a ring-closing moietyselected from a phthalide and a naphthalide.

The indicator dyes represented above may contain one or moresubstituents in addition to those specified as may be readily selectedby those skilled in the art to achieve certain desired properties.Typical substituents include branched or straight chain alkyl, such as,methyl, ethyl, isopropyl, n-butyl, t-butyl, hexyl, octyl, dodecyl,hexadecyl, octadecyl and eicosanyl; aryl, such as, phenyl,2-hydroxyphenyl, 2-hydroxy-4-dodecyloxyphenyl, and naphthyl; alkaryl,such as, benzyl, phenethyl, phenylhexyl, p-octylphenyl, p-dodecylphenyl;alkoxy, such as, methoxy, ethoxy, butoxy, 1-ethoxy-2-(β-ethoxyethoxy),dodecyloxy and octadecyloxy; aryloxy, such as, phenoxy, benzyloxy,naphthoxy; alkoxyalkyl, such as methoxyethyl, dodecyloxyethyl; halo,such as, fluoro, bromo, and chloro; trifluoralkyl, such as,trifluoromethyl, mono- and bis-trifluoromethyl carbinol; sulfonamido;sulfamoyl; acyl and its derivatives; aminomethyl; amido; sulfonyl;sulfo; cyano; nitro; amino including mono- and disubstituted amino,e.g., N-ethyl amino and N,N'-dimethylamino; caroboxy; and hydroxyl.

As mentioned previously, the indicator dyes produced in accordance withthe present invention may be symmetrical in which instance the B radicalwould be a naphthol radical identical to A, or they may be unsymmetricalor mixed indicators. When unsymmetrical, the A radical and B radicalboth would be derived from a 1-naphthol, but each radical would containdifferent substituents or the same substitutents in different positionsor one radical would be substituted and the other unsubstituted. Theterm "mixed indicator" is intended to denote indicator dyes where the Aradical and B radical are derived from different aromatic compounds, andin this instance, one from naphthol and the other from indole.

For use as optical filter agents in photographic processes, such as,diffusion transfer processes employing highly alkaline processingsolutions, it may be desirable that the indicator dye selected as theoptical filter agent possess a relatively high pKa so that the dye willbe in a light-absorbing form during the initial stages of processing andyet may be rendered substantially non-light absorbing within arelatively brief interval as the pH subsequent to substantial imageformation is reduced in order to permit early viewing of the image. Suchdyes may be prepared according to the present invention by appropriateselection of the reactants to provide in the final dye, an A and/or Bradical possessing a hydrogen-bonding group adjacent to the functional--OH of the naphthol radical or adjacent to the --NH-- of the indoleradical. For example, indicator dyes of Formula I above wherein the Aradical possesses a hydrogen-bonding group substituted on the carbonatom ortho to the naphtholic --OH possess a relatively high pKa whichmakes them useful as optical filter agents in the aforementionedprocesses.

The association of two atoms through hydrogen to form a hydrogen bondbetween or within molecules is well known. When hydrogen is attached toan electronegative atom, for example, O or N, the resultant bond ispolarized. If directed toward another atom (M) with an unshared pair ofelectrons, the hydrogen acts as a bridge between the atoms (O-H . . . M)due to the electrostatic attraction to both atoms between which thehydrogen proton can be transferred. In the compounds noted above, anintramolecular hydrogen bond is formed between the p-hydroxy group andthe adjacent hydrogen-bonding group, i.e., a group containing aheteroatom possessing an active unshared pair of electrons, such as, O,N, S or halogen, e.g., F., which has a free electron pair or a negativecharge in basic solution and which is capable of forming a 5-, 6- or7-membered and preferably a 5- or 6- membered hydrogen-bonded ring withthe functional, i.e., naphtholic --OH. Preferably, the heteroatom in thehydrogen-bonding group has attached to it a proton which is more acidicthan the proton on the naphtholic --OH and ionizes in basic solution toa negative charge. Such groups include, for example, carboxy; hydroxy;o-hydroxyphenyl; bis trifluoromethyl carbinol; sulfonamido (--NH--SO₂--R') and sulfamoyl (--SO₂ --NH--R"). R' and R" usually contain up toabout 20 carbon atoms and may be alkyl, aryl, aralkyl and alkaryl.Typical R' and R" substituents include branched or straight chain alkyl,e.g., methyl, ethyl, isopropyl, n-butyl, t-butyl, hexyl, octyl, dodecyl,hexadecyl, octadecyl and eicosanyl; aryl, e.g., phenyl and naphthyl; andaralkyl and alkaryl, particularly alkyl-substituted phenyl andphenyl-substituted alkyl, e.g., benzyl, phenethyl, phenylhexyl,p-octylphenyl and p-dodecylphenyl.

Naphthol indicator dyes which are particularly useful as optical filteragents in diffusion transfer photographic processes are those wherein atleast one and preferably both of the naphthol radicals possess a carboxygroup adjacent to the naphtholic --OH as produced in accordance with thepreferred embodiment of the present method. Since naphthol naphthaleinshave a higher pKa than the corresponding naphthol phthaleins, thecarboxynaphthol naphthalides are particularly preferred for use inhighly alkaline photographic processing compositions. For example,3,3-bis(-3'-carboxy-4'-hydroxy-1'-naphthyl)phthalide has a pKa ofapproximately 12.5 whereas3,3-bis(3'-carboxy-4'-hydroxy-1'-naphthyl)naphthalide has a pKa of about13.5. High pKa naphthol phthaleins and naphthaleins substituted withhydrogen-bonding groups including carboxy-naphthol indicator dyes formthe subject matter of copending U.S. Pat. application Ser. No. 103,865filed Jan. 4, 1971, now U.S. Pat. No. 3,833,614.

Specific examples of 1-naphthol indicator dyes that may be preparedaccording to the method of the present invention are as follows:##SPC10## ##SPC11##

The novel intermediates of the present invention are the(na)phthalidylnaphthols obtained as the reaction product of a 1-naphtholand a (na)phthalaldehydic acid as represented in formula (II) and theleuco dye intermediates obtained as the reaction product of the(na)phthalidylnaphthol and a 1-naphthol or indole as represented informula (III). ##SPC12##

wherein A represents 4'-hydroxy-1'-naphthyl and X represents the atomsnecessary to complete a ring-closing moiety selected from a phthalideand a naphthalide and preferably is naphthalide; ##SPC13##

wherein A represents 4'-hydroxy-1'-naphthyl; B represents4'-hydroxy-1'-naphthyl or indol-3-yl and C represents a2-carboxy-1-phenyl radical or an 8-carboxy-1-naphthyl radical andpreferably is 8-carboxy-1-naphthyl. It will be appreciated that theabove intermediates may contain one or more substitutents as ultimatelydesired in the complete dye, such as those enumerated above.

In a preferred embodiment, the intermediates of the present inventionpossess naphthalide as the ring-closing moiety and comprise compounds asrepresented by the following formulas: ##SPC14##

wherein R¹ and R² each are selected from hydrogen and a hydrogen-bondinggroup, at least one of R¹ and R² being hydrogen. Preferably, R¹ ishydrogen and R² is hydrogen or a hydrogen-bonding group forming a 5-, 6-or 7-membered intramolecular hydrogen-bonded ring with the adjacent --OHand preferably is a hydrogen-bonding group selected from carboxy,hydroxy, o-hydroxyphenyl, bis trifluoromethyl carbinol, sulfonamido andsulfamoyl. ##SPC15##

wherein R¹ and R² each are selected from hydrogen and a hydrogen-bondinggroup, at least one of R¹ and R² being hydrogen. Preferably, R¹ ishydrogen and R² is hydrogen or a hydrogen-bonding group and Brepresents. ##SPC16##

wherein R³ and R⁴ each are selected from hydrogen and a hydrogen-bondinggroup, at least one of R³ and R⁴ being hydrogen, R⁶ and R⁷ each areselected from hydrogen and a hydrogen-bonding group, at least one of R⁶and R⁷ being hydrogen and R⁵ is selected from hydrogen and alkoxycontaining 1 to 18 carbon atoms. The hydrogen-bonding group preferablyforms a 5-, 6- or 7-membered intramolecular hydrogen-bonded ring withthe adjacent --OH of the 4'-hydroxynaphthyl radical (or with theadjacent --NH-- of the indolyl radical) and preferably is ahydrogen-bonding group selected from carboxy, hydroxy, o-hydroxyphenyl,bis trifluoromethyl carbinol, sulfonamido and sulfamoyl. Where it isdesired to employ the above classes of intermediates in the preparationof indicator dyes having a relatively high pKa, R² of A is preferably ahydrogen-bonding group and for obtaining a further increase in the pKaof the indicator dye product, R³ or R⁴ of the 4'-hydroxy-naphthylradical B or R⁶ or R⁷ of the indolyl radical B is a hydrogen-bondinggroup.

Specific examples of the novel leuco dye intermediates of the presentinvention include: ##SPC17## ##SPC18##

Specific examples of p-(na)phthalidyl intermediates of the presentinvention include: ##SPC19##

The p-(na)phthalidyl naphthol employed in step 1 of the present methodmay be prepared by reacting a 1-naphthol and the selected acid, i.e.,the phthalaldehydic or naphthalaldehydic acid in substantially equimolarproportions in an organic solvent in the presence of a external acidcatalyst, such as, zinc chloride, toluene-p-sulfonic acid,trifluoroacetic acid and trichloroacetic acid. Other suitable condensingacids include hydrochloric and sulfuric acids, preferably the anhydrousacids. For example, sulfuric acid has been used by Brubaker, et al., J.Amer. Chem. Soc., 49, 2279 (1927) in the preparation of p-phthalidylphenols by the condensation of certain phenolic compounds ando-phthalaldehydic acid. The aldehydic acid and the 1-naphthol maycontain substituents provided, of course, that the 1-naphthol has a freeposition para to the naphtholic --OH for reaction with the(na)phthalaldehydic acid. The reaction temperature may vary over arelatively wide range from room temperature, i.e., about 20°C. up toelevated temperatures of about 120°C. which may be readily determinedfor the particular reactants. To achieve practical reaction rates, it ispreferred to conduct the reaction at elevated temperatures but belowtemperatures at which decomposition of starting materials and/or sidereactions and by-products tend to occur. The solvent used may be any ofthe inert organic liquids commonly employed for this condensationreaction, such as, glacial acetic acid, tetrahydrofuran, nitromethane,toluene, methylene chloride, and benzene.

In carrying out step 1 of the present method, the p-(na)phthalidylnaphthol and the 1-naphthol or indole are reacted in solution in thepresence of base at a pH of at least about the pKa, i.e. thedissociation constant of the (na)phthalidyl naphthol. In the case ofnaphthols, the pH selected is substantially the same as or above thepKa's of the (na)phthalidyl naphthol and 1-naphthol reactants. In thecase of indoles which are good nucleophiles, the pH selected isapproximately the same as the pKa of the (na)phthalidyl naphthol. Thus,the particular base and its concentration will be selected to providethe appropriate pH for the particular reactants employed. Ordinarily,the base is used in aqueous solution or in aqueous organic solution. Forexample, an aqueous or aqueous alkanol solution of between about 5% and25% by weight sodium hydroxide has been found satisfactory for thereaction of a (na)phthalidyl naphthol and a 1-naphthol having pKa's inthe vicinity of 12 to 14. It will be appreciated that other bases may beemployed, for example, other hydroxides, such as, potassium and lithiumhydroxides and that the base selected may be in organic and usuallyaqueous or aqueous-organic media as appropriate for forming a solutionof the base and reactants.

The (na)phthalidyl naphthol may be reacted with equimolar amounts orwith an excess of the 1-naphthol or indole, usually in the proportion ofabout 1.0 to 2.0 moles of naphthol or indole per mole of (na)phthalidylnaphthol. It will be understood that the 1-naphthol will have a freeposition para to the naphtholic --OH and that the indole will have afree 3-position for forming the corresponding 4'-hydroxy-1'-naphthyl andindol-3-yl B radical in the leuco intermediate and final dye product.The reaction temperature may vary over a relatively wide range,depending upon the reactants, and is usually between about 20°C. and100°C. For example, the reaction of (na)phthalidyl naphthol and indoleproceeds quite readily at room temperature whereas the reaction of the(na)phthalidyl compound with a 1-naphthol preferably is conducted atelevated temperatures of about 50°C. or higher. In the production ofcarboxy-naphthol dyes, a reaction temperature of between about 50°C. and70°C. is preferred to achieve a practical reaction rate together withoptimum product yields.

As noted previously, in the preparation of the dicarboxy-naphtholindicator dyes, the naphtholic --OH groups of the leuco dye intermediateobtained in step 1 preferably are ionized prior to oxidation of theintermediate to form the indicator. By ionizing the naphtholic groupsfirst, the methane hydrogen may be removed more readily therebyfacilitating the oxidation step. Ionization may be carried out in aknown manner, for example, by treating with a basic reagent capable ofionizing the naphtholic groups in the solvent selected. Typical basicreagents include an organic base, such as, N,N,N',N'-tetramethyl-1,8-diaminonaphthalene or an inorganic base, such as,sodium hydroxide, sodium hydride, sodium methoxide, potassium hydroxide,and potassium t-butoxide. Sodium and potassium hydroxide, are generallyused in aqueous solution. To achieve better yields, the ionizationpreferably is carried out in organic solution, for example, sodiummethoxide in ethanol, potassium t-butoxide in t-butanol, and thetetramethyldiaminonaphthalene or sodium hydride or potassium t-butoxidein a non-protonic organic solvent, such as, dimethylsulfoxide,N,N-dimethyl-formamide or dimethoxyethane. It will be appreciated thatit may be desirable to include the ionization step in the preparation ofdyes other than the dicarboxy-naphthols to facilitate oxidation of theleuco dye intermediate, particularly where both the A and B radicals ofthe leuco dye are derived from naphthols.

The oxidation of step 2 may be carried out using any conventionaloxidizing agent and is most conveniently carried out by simply addingthe selected agent(s) to the reaction mixture containing the leuco dyeor the ionized leuco dye intermediate. Examples of oxidizing agents thatmay be employed include gaseous oxygen, silver oxide, silver acetate,potassium persulfate, lead acetate, lead oxide, manganese dioxide,sodium chromate and potassium peroxydisulfate which oxidants are usuallyadded to aqueous solutions of the intermediate. Oxidizing agents whichordinarily are added to organic solutions of intermediate include, forexample, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, o-chloranil, andchloranil.

The ionization and oxidation steps may be carried out at roomtemperature or above and usually between about 20°C. and 100°C. Theappropriate temperature for achieving optimum results may be readilydetermined for the particular leuco dye intermediate. Though notessential, any or all of the steps of the present method and preferably,the base-catalyzed addition of step 1 is conducted under an inertatmosphere, e.g., nitrogen.

In another embodiment, the general reaction scheme detailed above may beemployed in the production of indicator dyes wherein the naphthalidering-closing moiety is substituted with a sulfonamido substituent. Inthe production of such dyes, 6-nitronaphthalaldehydic acid is reactedwith a 1-naphthol to form the corresponding 1:1 adduct. The nitro groupis reduced to an amino group prior to step 1 and the amino group isconverted to a sulfonamido group subsequent to step 2 as shown in thefollowing sequence illustrating the preparation of abis(3'-carboxy-4'-hydroxynaphthyl)-6-sulfonamidonaphthalides. ##SPC20##

In the embodiment illustrated above, the 6-nitronaphthalaldehydic acidmay be synthesized in a known manner by reacting naphthalaldehydic acidwith potassium nitrate in sulfuric acid solution. After forming the 1:1adduct with a 1-naphthol and prior to step 1, the nitro group may bereduced to an amino group by treating with a reducing agent such asstannous chloride, by introducing gaseous hydrogen in the presence of ahydrogenation catalyst or in any other suitable and convenient manner.Converting the amino group to a sulfonamide group also may be carriedout in a conventional manner by reacting the selected sulfonyl chloridewith the 6-aminonaphthalide indicator dye in aqueous and/or inertorganic media and preferably, in aqueous media to facilitate isolationof the sulfonamido dye product.

The sulfonyl chloride (R--SO₂ Cl) employed may contain as the Rsubstituent, an alkyl, aryl, aralkyl or alkaryl group. Like R' and R",the R group usually contains up to about 20 carbon atoms but may containa greater number of carbon atoms as may be desired. For example, thesulfonamido group on the ring-closing portion of the dye provides aconvenient means for adjusting the diffusibility of the dye in aqueoussolution by selecting an R group to give the degree of mobility desired.The alkyl group or the alkyl portion of the alkaryl group may bebranched or straight chain, and preferably is straight chain where thesulfonamido group is being utilized to render the dye substantiallynon-diffusible in the processing solution. Examples of groups that maycomprise R include alkyl, such as, methyl, ethyl, propyl, isopropyl,sec-butyl, tert-butyl, hexyl, octyl, decyl, dodecyl, hexadecyl,octadecyl and eicosanyl; aryl, such as, phenyl and naphthyl; aralkyl andalkaryl, particularly phenyl-substituted alkyl and alkyl-substitutedphenyl, such as, benzyl, phenethyl, phenylhexyl, p-hexylphenyl,p-octylphenyl and p-dodecylphenyl.

The following examples are given to further illustrate the presentinvention and are not intended to limit the scope thereof.

EXAMPLE 1

Preparation of the compound of Formula 29:

a. 13.1 g. of potassium nitrate was dissolved in 75 ml. of sulfuricacid. This solution was added dropwise to a cooled (5°C.) solution of23.8 g. of naphthalaldehydic acid in 175 ml. of sulfuric acid, whilemaintaining the temperature at 50°C. throughout addition. The reactionmixture was refrigerated overnight. It was then poured into ice water(about 400 ml.). A light yellow solid was obtained. The solid wasdissolved in about 500 ml. of 1,2-dimethoxyethane, and after evaporatingthe solvent down to about half the volume,3-hydroxy-6-nitronaphthalide-1,8 was obtained as beige crystals.

b. A mixture of 3-hydroxy-6-nitronaphthalide-1,8 (6.12 g.; 0.025 m.)prepared above and 1-hydroxy-2-naphtholic acid (4.7 g.; 0.025 m.) in 100ml. of 12% p-toluenesulfonic acid in acetic acid solution was heated toreflux. After about one hour the reactants were in solution and then ayellow solid formed. After refluxing for an additional two hours, thereaction solution was cooled, and the yellow solid was removed byfiltration and recrystallized from methyl cellosolve to yield 8.3 g.(67% by weight) of3-(3'-carboxy-4'-hydroxynaphthyl)-6-nitronaphthalide-1,8, melting range255°-258°C.

c. 3-(3'-carboxy-4'-hydroxy-1'-naphthyl)-6-nitronaphthalide-1,8 (4.15g.; 0.01 m.) as prepared in step (b) was heated in 120 ml. of methylcellosolve until the naphthalide was dissolved. The resulting solutionwas cooled to room temperature. Stannous chloride (6.78 g.; 0.03 m.)dissolved in hydrochloric acid (20 ml.) was added dropwise to thesolution, and the solution was stirred overnight at room temperature.The reaction mixture was poured into ethyl acetate (about 250 ml.) andthe ethyl acetate solution extracted several times with water until someorange solid precipitated. Then the ethyl acetate was removed byevaporation leaving an orange oil that crystallized upon standing toyield 2.5 g. of the corresponding 6-aminonaphthalide. (65% by weightyield).

d. The 3-(3'-carboxy-4'-hydroxy-1'-naphthyl)-6-aminonaphthalide-1,8prepared above (4.8 g.; 0.012 m.) and 1-hydroxy-2-naphthoic acid (4.5g.; 0.024 m.) were added to a deareated aqueous sodium hydroxidesolution (7.6% NaOH) under nitrogen. The resulting solution was heatedto 70°C. for 5 hours after which time no aminonaphthalide remained. Thesolution was then poured into water and extracted several times at pH8-10 with ethyl acetate to remove any remaining 1-hydroxy-2-naphthoicacid and at pH 6-8 to remove other impurities. The pH was then adjustedto below pH 6 by the addition of 10% aqueous hydrochloric acid. Thesolution was extracted with ethyl acetate and upon evaporation of thesolvent, 4.95 g. of leuco compound was obtained (67.5% by weight yield).

e. To the leuco compound prepared above (9.5 g.; 0.017 m.) in 500 ml. ofdimethylsulfoxide under nitrogen, was added portionwise a 50% solutionof sodium hydride (4.1 g.; 0.017 m.) in oil. The mixture was heated to60°C. for 1 hour until no more reaction was apparent. After cooling toroom temperature, silver acetate (100 mg.) was added and then potassiumpersulfate (4.6 g.). Upon heating for 15 minutes, the mixture turnedblue. The reaction mixture was then filtered over Celite, and ice waterwas added to the filtrate which was acidified with dilute hydrochloricacid. The flocculent beige solid that formed was extracted with ethylacetate several times. The first two extracts yielded a small amount ofgrey solid impurity. Further extractions, upon evaporation of the ethylacetate, gave a brown oil which when taken up in methanol and with wateradded, yielded the corresponding naphthalide compound as a yellow solid(6.5 g.; 68.4% by weight yielded).

f. 2.30 g. of3,3-bis-(3'-carboxy-4'-hydroxy-1'-naphthyl)-6-amino-naphthalide of step(e) was dissolved in water (25 ml.) and 1N aqueous sodium hydroxidesolution (6 ml.). Acetone (10 ml.) was added and a combination pHelectrode inserted. The pH was adjusted to 8.5 by adding 1N sodiumhydroxide. The solution was stirred and para-n-dodecylbenzenesulfonylchloride (1.40 g.) was added. The mixture was warmed to 40°C., andstirring was continued. The pH which had slowly dropped to about 7.5 wasadjusted to 8.5 by adding 1N sodium hydroxide solution. The mixture wasstirred overnight under nitrogen at 40°C. The pH which had dropped toabout 3.5 was adjusted to 8.5 with 1N sodium hydroxide and an additional0.70 g. the sulfonyl chloride was added. Reaction was continued forabout 8 hours with the pH reading held between 7.5 and 8.5. The mixturewas then cooled and filtered to remove a crystalline solid. The filtratewas diluted with 100 ml. of water and mixed with 100 ml. of ethylacetate. The pH of the mixture was adjusted to 7.0 with dilutehydrochloric acid. The layers were separated and the lower layer wasstirred with 100 ml. of fresh ethyl acetate and the pH was adjusted to6.0. The ethyl acetate layer was separated, washed with dilutehydrochloric acid and then washed with water. The ethyl acetate solutionwas dried over magnesium sulfate; filtered and evaporated to give thetitle compound (0.60 g.).

EXAMPLE 2

Preparation of the compound of formula 22.

a. A mixture of 3.6 gms. of diisopropylethylamine and 3.6 gms. ofn-propylamine was added dropwise to 7.3 gms. of1-carbomethoxynaphthalene-2-sulfonyl chloride in 25 ml. of chloroformwhile maintaining the temperature between 50° and 60°C. The resultingsolution was kept at 50°-60°C. for 15 minutes at which time aprecipitate began to form. Heating was continued for an additional 30minutes. The solution was then cooled, acidified with 10% hydrochloricacid and the chloroform evaporated. Three recrystallizations of theresidue from benzene-hexane yielded about 4.5 gms. of2-n-propylsulfamoyl-1-naphthol (melting range 61°-64°C.).

b. A mixture of 2.4 gms. of the sulfamoyl intermediate prepared in step(a) above and 1.8 gms. of naphthalaldehydic acid were dissolved in 30ml. of acetic acid and 30 ml. of 12% p-toluene sulfonic acid in aceticacid was added. The resulting solution was heated at reflux overnight.The reaction mixture was poured into an equal volume of cold water. Theprecipitate formed was collected and recrystallized from abenzene-petroleum ether mixture to yield 3.0 gms. of solid (meltingrange 189°-191°C.)

c. A solution of 50 ml. of aqueous 10% sodium hydroxide was flushed withnitrogen for 2 hours. To the solution was added 2.3 gms. of the productof step (b) and 1.4 gms. of 2-n-propyl-sulfamoyl-1-naphthol as preparedin step (a). The resulting solution was heated at 60°C. overnight. Thetemperature was raised to 70°C. and heating was continued for about 48hours. The reaction mixture was then cooled and the pH adjusted toapproximately 1.0 with dilute hydrochloric acid. The white solids formedwere collected and washed and taken up in benzene. The benzene solutionwas treated with charcoal, filtered and concentrated until solids beganto precipitate. The precipitate was collected yielding 2.5 gms. of whitesolid (melting range 178°-180°C. dec.).

d. 710 mgs. of the product of step (c) were dissolved in about 30 ml. ofdimethylformamide. To this was added 230 mgs. of 57% sodium hydride. Theresulting solution was heated at 80°C. until the evolution of hydrogenhad ceased. Then 470 mgs. of silver oxide was added, and the mixture wasstirred overnight at room temperature. Heating was continued at 80°C.for 8 hours. The reaction mixture was filtered, and the filtrate pouredinto 30 ml. of water, acidified with dilute hydrochloric acid and theprecipitate collected. The precipitate was taken up in benzene andchromatographed on silica gel. Elution with 10% ethyl acetate in benzeneyielded about 100 mgs. of the title compound.

EXAMPLE 3

Preparation of the compound of the formula 1.

a. A solution of 61 g. of sodium hydroxide and enough water to give 350ml. of solution was purged by bubbling nitrogen through the solution. Tothis was added 30.0 g. of3-(3'-carboxy-4'-hydroxy-1'-naphthyl)naphthalide and 10.0 g. of1-hydroxy-2-naphthoic acid (2-carboxy-1-naphthol). The solution wasstirred and heated at 50°C. for 23 hours. An additional 5.0 g. of1-hydroxy-2-naphthoic acid was added; the temperature increased to70°C.; and heating continued 41/2 hours. The solution was cooled, mixedwith 300 ml. of water and 400 ml. of ethylacetate. The pH of the stirredmixture was adjusted to 8.0 with aqueous hydrochloric acid. The ethylacetate was separated and discarded. This procedure was repeated. (Thediscared extracts contained mainly 1-hydroxy-2-naphthoic acid.) Another400 ml. of ethyl acetate was added; the pH was adjusted to 6.5 withaqueous hydrochloric acid. The ethyl acette was separated, washed withcold dilute hydrochloric acid, then with water, then dried overmagnesium sulfate. Evaporation followed by ethyl acetate washing of thesolid yielded 32.0 g. of leuco dye intermediate. This was satisfactoryfor conversion to the indicator dye but may be recrystallized from 50/50ethyl acetate: 1,2-dimethoxyethane.

b. A solution of 9.97 of the above leuco dye intermediate in 170 ml. ofmolecular sieve dried dimethylsulfoxide was purged by bubbling nitrogenthrough it. The solution was treated with 4.37 g. of 54% by weightsodium hydride dispersion. When gas evolution had ceased, 4.84 g. ofpotassium peroxydisulfate was added all at once and the solution stirredfor 31/2 hours. The solution was then made strongly acidic with aqueoushydrochloric acid, then diluted to 500 ml. with water. The tan solidwhich formed was collected and washed with water. The solid wasdissolved in 300 ml. of water by adding aqueous sodium hydroxidesolution to a pH of approximately 12. The solution was stirred with 300ml. of ethyl acetate, and the pH was adjusted to 7.0 with dilutehydrochloric acid. The ethyl acetate was separated and discarded and theprocedure was repeated beginning with the addition of 300 ml. of freshethyl acetate. The water layer was then stirred, acidified to pH 1, andleft overnight. The tan solid was collected and recrystallized fromethanol-water mixture to give 4.2 g. of the title compound as a whitesolid.

EXAMPLE 4

Preparation of the compound of the formula 35.

a. A solution containing 5.00 g. of 2-(o-hydroxyphenyl)indole, 9.20 g.of 3-(3'-carboxy-4'-hydroxy-1'-naphythyl)naphthalide and 3.95 g. ofsodium hydroxide in 100 ml. of water was stirred overnight at roomtemperature under nitrogen. Some starting material remained. Thesolution was then heated for two hours at 50°C., cooled to 20°C.,neutralized to pH 7, filtered and acidified to pH 1. The acidifiedsolution was extracted with ethyl acetate. The ethyl acetate solutionwas washed with water, dried over magnesium sulfate and evaporated to anoil. Treatment of the oil with benzene produced the leuco dyeintermediate as a white solid, yield 2.0 g.

b. To a solution of 1.0 g. of the above dye intermediate in 20 ml. ofdry 1,2-dimethoxybenzene under nitrogen was added 0.40 g. of2,3-dichloro-5,6-dicyanobenzoquinone. After heating one hour at reflux,the solution was cooled and the title compound separated as a nearlywhite solid, 0.40 g.

EXAMPLE 5

Preparation of the compound of the formula 36.

The title compound was prepared according to the procedure of Example 4by reacting 5-n-dodecyloxy indole with3-(3'-carboxy-4'-hydroxy-1'-naphthyl)naphthalide.

The 3-(3'-carboxy-4'-hydroxy-1'-naphthyl)naphthalide employed inExamples 3 to 5 was prepared as follows: Naphthalaldehydic acid, 40.0 g.(0.20 moles), 1-hydroxy-2-naphthoic acid, 37.6 g. (0.20 moles), and 12%p-toluenesulfonic acid in acetic acid (600 ml.) were mixed in a flaskequipped with a stirrer and a reflux condenser closed by a calciumsulfate drying tube. The mixture was refluxed for 5 hours, poured intoice water and the resulting solid was collected by filtration, washedwith water and air dried. The solid was recrystallized from methylcellosolve to give 43 g. of the product, a nearly while crystallinesolid.

It will be appreciated that other 1-naphthols such as those containing ahydrogen-bonding group substituted in the 2- or 8-position may beemployed to provide the corresponding A or B radical in the aboveexamples, and also, that other indoles, such as those substituted in the2- or 7-position with a hydrogen-bonding group may be employed toprovide the corresponding B radical. For preparing phthalides,phthalaldehydic acid or phthalaldehydic acid substituted with, e.g.,carboxy may be substituted for naphthalaldehydic acid in the aboveexamples.

As noted previously, naphthol phthaleins and naphthaleins wherein one orboth of the naphthol radicals is substituted with certain groups, suchas, a carboxy group, form the subject matter of copending applicationSer. No. 103,865 of Myron S. Simon filed Jan. 4, 1971, now U.S. Pat. No.3,833,614. Mixed phthaleins and naphthaleins comprising one indoleradical and one p-hydroxycarbocyclic aryl radical derived from a phenolor a 1-naphthol comprise the subject matter of copending applicationSer. No. 202,558 of Eva R. Karger and Paul T. MacGregor filedconcurrently herewith, now U.S. Pat. No. 3,816,124.

The indicator dyes produced in accordance with the present invention maybe employed in analytical procedures where phthalein indicators arecommonly used, for example, to measure changes in pH value and findother uses as well. As discussed in copending U.S. Pat. applicationsSer. No. 108,260 filed Jan. 21, 1971, now U.S. Pat. No. 3,702,244 issuedNov. 7, 1972 and Ser. No. 103,392 filed Jan. 4, 1971, now U.S. Pat. No.3,702,245 issued Nov. 7, 1972, it has been found that a selectivelyexposed photosensitive material having a latent image therein may beprocessed in the presence of extraneous incident radiation actinicthereto by reason of the protection afforded by suitably positioningwith respect to the exposure surface of the photosensitive layer aneffective concentration of a selected dye or dyes as optical filteragents. The use of certain indole dyes including indole phthalides andnaphthalides as optical filter agents for protecting photosensitivematerials from radiation in the shorter wavelength region of the visiblespectrum forms the subject matter of aforementioned application Ser. No.108,260. The use of certain dyes derived from phenolic compoundsincluding 1-naphthol phthalides and naphthalides as optical filteragents for protecting photosensitive materials from radiation in thelonger wavelength region of the visible spectrum forms the subjectmatter of aforementioned application Ser. No. 103,392.

Since certain changes may be made in the above process and productswithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description shall beinterpreted as illustrative and not in a limiting sense.

What is claimed:
 1. A compound of the formula: ##SPC21##wherein R¹ andR² each are selected from hydrogen and a hydrogen-bonding group selectedfrom carboxy, hydroxy, o-hydroxyphenyl, bis trifluoromethyl carbinol,sulfonamido and sulfamoyl, at least one of R¹ and R² being hydrogen. 2.A compound as defined in claim 1 wherein R¹ is hydrogen and R² is ahydrogen-bonding group.
 3. A compound as defined in claim 2 wherein R²is carboxy.
 4. A compound as defined in claim 2 wherein R² is sulfamoyl.5. A compound as defined in claim 4 wherein said sulfamoyl isn-propylsulfamoyl.